The invention relates generally to cellular communications networks and, more specifically, to controlling operations of a cellular communications network having airborne transceivers.
Terrestrial cellular communications networks have provided convenient wireless communications services for years. These services include, for example, cellular telephone services, paging, Internet access, and data transfer services, among others.
FIG. 1 illustrates a simplified block diagram of a terrestrial cellular communications network 100, in accordance with the prior art. Network 100 includes one or more base station antennas 102 coupled to base transceiver stations (BTS) 103. Each BTS 103 communicates, via antennas 102 and subscriber links 104, with cellular communication units carried by mobile users 106. Essentially, the BTS modulates and demodulates the information exchanged on the subscriber links 104, and it converts signals to and from the format used over the subscriber links. Subscriber links 104 may support a time division multiple access (TDMA, e.g. IS-136, GSM), code division multiple access (CDMA, e.g. IS95), or other type of digital or analog communication protocol.
BTS 103 also are coupled to a mobile switching office (MSO) 110. This can be a direct connection (e.g., using fiber optic or telephone (e.g., T1) links 105), or the connection 108 can be chained through other BTS.
When data originates from or is destined for a public switched telephone network (PSTN, not shown), this data is routed through a mobile switching office (MSO) 110. Essentially, the MSO 110 includes a switch that interfaces the cellular network and the PSTN.
Network 110 is optimized via various performance parameters. For example, these performance parameters include power control parameters, handoff parameters (e.g., thresholds, averaging parameters, and hysteresis), access parameters (e.g., the minimum received signal level required before a communication unit is granted access to the system), handoff candidate information for neighboring cells, and the designation of which channels are control channels and which are traffic channels.
In a well-designed network, these performance parameters are selected to achieve near optimal network performance. Usually, these performance parameters are determined only when major changes in the network configuration occur, such as during network installation or when additional cell sites are added (e.g., to improve network coverage or capacity). In a terrestrial network, thus, the network optimization process is relatively static. This is considered acceptable, because the network infrastructure and communications quality are considered to be relatively stable. The infrastructure is geographically fixed in a terrestrial cellular network, and the communications quality is not substantially affected by or the system design considers variables such as weather (e.g., thunderstorms, high winds).
In order to increase capacity in a terrestrial cellular network, additional BTS must be added to the network. Adding such additional equipment may take weeks or months, and in some cases it is impossible to incorporate new equipment into an existing infrastructure. Therefore, prior art terrestrial networks cannot rapidly respond to a level of user demand that exceeds the network""s then-current capacity. . . .
What is needed is a cellular communications network that is able to more rapidly respond to changing capacity demands by quickly modifying network infrastructure or configuration. Further needed is a method for rapidly determining performance parameters for a modified network infrastructure or configuration and quickly implementing the parameters"" use so that optimal network performance can be continuously maintained.